Composition for overcoat layer of organophotoreceptor, organophotoreceptor manufactured by employing the same and the electrophotographic imaging apparatus containing the same

ABSTRACT

A composition for an overcoat layer suitable for use in an organophotoreceptor for liquid toner, an organophotoreceptor manufactured by employing the composition and an electrophotographic imaging apparatus containing the organophotoreceptor. Since the organophotoreceptor can maintain higher charge potential and low residual or discharge potential, the lifetime of the organophotoreceptor can be extended. Also, since the organophotoreceptor has good solvent resistance and abrasion resistance, it can be advantageously used for liquid toner.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent ApplicationNo. 2002-61490, filed Oct. 9, 2002, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a composition for an overcoatlayer of an organophotoreceptor, an organophotoreceptor manufactured byemploying the same and an electrophotographic imaging apparatuscontaining the same. More specifically, the invention relates to acomposition for an overcoat layer suitable for use in anorganophotoreceptor for liquid toner, the composition having goodelectrical properties and increased abrasion resistance and adhesion toextend the lifetime of an organophotoreceptor. The present inventionalso relates to an organophotoreceptor manufactured by employing thecomposition and an electrophotographic imaging apparatus containing theorganophotoreceptor.

[0004] 2. Description of the Related Art

[0005] In electrophotography, an organophotoreceptor has an electricallyinsulating photoconductive element on an electrically conductivesubstrate and may be in the form of a plate, disk, sheet, belt, drum orthe like. An electrophotographic imaging process using theorganophotoreceptor will now be described briefly.

[0006] First, the surface of an organophotoreceptor having anelectrically conductive substrate where a charge transport material andcharge generating material are provided is electrostatically charged,and then the charged surface is imagewise exposed to light. The lightexposure selectively dissipates the charge in illuminated areas, therebyforming a pattern of charged and uncharged areas. Finally, a toner isthen deposited on the surface to create a toner image on the surface ofthe substrate. The resulting toner image can be transferred to asuitable receiving surface such as paper. The imaging process may berepeated many times.

[0007] Both single layer and multilayer photoconductive elements havebeen used. In single layer embodiments, a charge transport material andcharge generating material are combined with a polymeric binder and thendeposited on the electrically conductive substrate. In multilayerembodiments, the charge transport material and charge generatingmaterial are in the form of separate layers, each of which canoptionally be combined with a polymeric binder, deposited on theelectrically conductive substrate. Two arrangements are possible. In onearrangement (the “dual layer” arrangement), the charge generating layeris deposited on the electrically conductive substrate and the chargetransport layer is deposited on top of the charge generating layer. Inan alternate arrangement (the “inverted dual layer” arrangement), theorder of the charge transport layer and charge generating layer isreversed.

[0008] In both the single and multilayer photoconductive elements, thepurpose of the charge generating material is to generate charge carriers(i.e., holes and/or electrons) upon exposure to light. The purpose ofthe charge transport compound is to accept at least one type of thesecharge carriers and transport them through the photosensitive layer inorder to facilitate discharge of a surface charge on the photoconductiveelement.

[0009] An organophotoreceptor may be easily worn due to friction betweentoner and a roller or a cleaning blade, which decreases the thickness ofthe organophotoreceptor, resulting in a reduction in lifetime. Toovercome this problem, an overcoat layer may be formed on theorganophotoreceptor.

[0010] In recent years, there has been an increase in the development ofelectrophotographic printers using liquid toners, making it is necessaryto develop organophotoreceptors for liquid toners. However, conventionalovercoat layers have been proposed to extend the lifetime of anorganophotoreceptor for dry toner. Therefore, there is still growingdemand for overcoat layers that can extend the lifetime of anorganophotoreceptor suitable for liquid toners, having improvedelectrical and mechanical properties.

SUMMARY OF THE INVENTION

[0011] According to an aspect of the present invention there is provideda composition for an overcoat layer of an organophotoreceptor, which canimprove electrical, and mechanical properties as well as increase thelifetime of the organophotoreceptor suitable for liquid toner.

[0012] Additional aspects and advantages of the invention will be setforth in part in the description which follows and, in part, will beobvious from the description, or may be learned by practice of theinvention.

[0013] In an aspect of the present invention, there is provided acoating composition for an overcoat layer of an organophotoreceptorcomprising polyaminoether, an electron transport material and analcoholic solvent.

[0014] The polyaminoether is preferably hydroxylated polyaminoether.

[0015] The polyaminoether is represented by the following formula, andis contained in an amount of 70 to 99 parts by weight based on 100 partsby weight of the solid content of an overcoat layer:

[0016] wherein n is an integer from 10 to 400.

[0017] The electron transport material may contain an electron transportmaterial represented by the following formula:

[0018] wherein A and B are independently one selected from the groupconsisting of a hydrogen atom, a halogen atom, a C2˜C30 substituted orunsubstituted alkoxycarbonyl group or a C2˜C30 substituted orunsubstituted alkylaminocarbonyl group, and the hydrogen atom in thebenzene ring can be substituted by halogen atom(s).

[0019] Examples of the alcoholic solvents include, but are not limitedto, 1-methoxy-2-propanol, methanol, ethanol, propanol, butanol andisopropanol, and are contained in an amount of 70 to 99 parts by weightbased on 100 parts by weight of the coating composition for an overcoatlayer.

[0020] In another aspect of the present invention, there is provided anorganophotoreceptor comprising an electrically conductive substrate, aphotosensitive layer formed on the electrically conductive substrate,and an overcoat layer formed by coating the composition for an overcoatlayer on the photosensitive layer and drying.

[0021] The overcoat layer may have a thickness of 0.01 to 5 μm, and thephotosensitive layer may be a single layer having both a chargegenerating material and a charge transport material or a double layer inwhich a charge generating layer containing a charge generating materialand a charge transport layer containing a charge transport material arelaminated.

[0022] In still another aspect of the present invention, there isprovided an electrophotographic imaging apparatus comprising a pluralityof support rollers, and an organophotoreceptor operably coupled to thesupport roller with motion of the support rollers resulting in motion ofthe organophotoreceptor, wherein the organophotoreceptor comprises anelectrically conductive substrate, a photosensitive layer formed on theelectrically conductive substrate, and an overcoat layer formed bycoating the composition for an overcoat layer on the photosensitivelayer and drying.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and/or other aspects of the invention will become apparentand more readily appreciated from the following description f thepreferred embodiments taken in conjunction with the accompanyingdrawings of which:

[0024]FIG. 1 is a diagram illustrating (not to scale) anorganophotoreceptor.

[0025]FIG. 2 is a schematic representation of an electrophotographicimaging apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Reference will now be made in detail to the aspects of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout. The aspects are described below in order to explain thepresent invention by referring to the figures.

[0027]FIG. 1 is a diagram illustrating (not to scale) anorganophotoreceptor 1 comprising an electrically conductive substrate 2,a photosensitive layer 3 formed on the electrically conductive substrate2, and an overcoat layer 4 formed on the photosensitive layer 3.

[0028] A coating composition for an overcoat layer suitable for use inthe organophotoreceptor according to the present invention, wherein theorganophotoreceptor comprises an overcoat layer manufactured byemploying the composition and an electrophotographic imaging apparatususing the organophotoreceptor, will now be described in detail.

[0029] The present invention provides a coating composition for anovercoat layer for an organophotoreceptor comprising polyaminoether, anelectron transport material and an alcoholic solvent.

[0030] The polyaminoether, a polymer having good oxygen permeationresistance, may be a hydroxylated polyaminoether, preferably, a compoundrepresented by the following formula:

[0031] wherein n is an integer from 10 to 400, preferably 10 to 90.

[0032] Preferably, the polyaminoether represented by the above formulahas a weight average molecular weight in the range of 4,000 to 160,000.If the weight average molecular weight of the polyaminoether representedby the above formula is out of the range specified above, coating of thecomposition for an overcoat layer is difficult to achieve or solubilityof the alcoholic solvent is undesirably poor.

[0033] The electron transport material is exemplified by a compoundrepresented by the following formula:

[0034] wherein A and B are independently one selected from the groupconsisting of a hydrogen atom, a halogen atom, a C2˜C30 substituted orunsubstituted alkoxycarbonyl group or a C2˜C30 substituted orunsubstituted alkylaminocarbonyl group, and the hydrogen atom in thebenzene ring is substitutable by halogen atom(s). The number of carbonatoms in the substituted or unsubstituted alkoxycarbonyl group or thesubstituted or unsubstituted alkylaminocarbonyl group is preferably inthe range of 2 to 15, more preferably 2 to 8.

[0035] The above compound may be exemplified by the following formulas:

[0036] The electron transport material that can be used for theorganophotoreceptor according to the present invention is not limited tothose stated herein and can be used alone or in a mixture of two or morekinds of those compounds.

[0037] The amount of the electron transport material may be in the rangeof 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight, basedon 100 parts by weight of the solid content of an overcoat layer. If theamount of the electron transport material is less than 0.1 parts byweight, the electron transporting capability of the overcoat layerdecreases, deteriorating electrostatic properties of theorganophotoreceptor. If the amount of the electron transport material isgreater than 50 parts by weight, abrasion resistance of the overcoatlayer may be lowered or solubility of the electron transport materialmay be undesirably poor.

[0038] The coating composition for an overcoat layer according to thepresent invention includes a solvent. Any solvent that can dissolvepolyaminoether can be used, and an alcoholic solvent is preferred.Examples of the solvent include at least one selected from the groupconsisting of 1-methoxy-2-propanol, methanol, ethanol, propanol, butanoland isopropanol. Preferably, 1-methoxy-2-propanol is used alone or amixed-solvent containing 1-methoxy-2-propanol and at least one alcoholicsolvent selected from the group consisting of methanol, ethanol, butanoland isopropanol, is used. The solvent is preferably contained in anamount of 70 to 99 parts by weight based on 100 parts by weight of thecoating composition for an overcoat layer. If the amount of the solventis less than 70 parts by weight, the overcoat layer is excessivelythick, and an exposure potential of the organophotoreceptor becomes highand a residual potential and an exposure potential sharply increaseduring charge-exposure-erase cycling. If the amount of the solvent isgreater than 99 parts by weight, the overcoat layer is overly thin,resulting in the deterioration of mechanical properties of the overcoatlayer, such that it may be easily worn. Also, if the amount of thesolvent is less than the range specified above, solubility of thesolvent is undesirably poor. If the amount of the solvent is greaterthan the range specified above, coating of the composition for anovercoat layer is difficult to achieve and the overcoat layer is toothin to function properly.

[0039] In the case of using the mixed-solvent consisting of1-methoxy-2-propanol and at least one alcoholic solvent, the alcoholicsolvent is preferably used in an amount of 1 to 30 parts by weight basedon 100 parts by weight of total content of 1-methoxy-2-propanol.

[0040] In another aspect of the present invention, there is provided anorganophotoreceptor having improved electrical, and mechanicalproperties as well as an increased lifetime by employing the overcoatlayer manufactured from the composition.

[0041] The organophotoreceptor according to the present inventionincludes an electrically conductive substrate, a photosensitive layerformed on the electrically conductive substrate, and an overcoat layerformed by coating the composition for an overcoat layer on thephotosensitive layer and drying.

[0042] Preferably, the photosensitive layer includes a charge transportlayer formed on the electrically conductive substrate and a chargegenerating layer formed on the charge transport layer.

[0043] The overcoat layer preferably has a thickness of 0.01 to 5 μm. Ifthe thickness of the overcoat layer is less than 0.01 μm, the overcoatlayer is not effective in protecting underlying layers. If the thicknessof the overcoat layer is greater than 5 μm, electrical propertiesthereof, including an increased exposure potential, may undesirablydeteriorate.

[0044] The photosensitive layer may have a single layer with both acharge transport material and a charge generating material or may have adouble layer in which a charge generating layer, containing a chargegenerating material, and a charge transport layer, containing a chargetransport material, are laminated.

[0045] A method of manufacturing an electrophotographicorganophotoreceptor using the composition for an overcoat layeraccording to the present invention will now be described.

[0046] A photosensitive layer is first formed on an electricallyconductive substrate. Here, the photosensitive layer may be formed bysequentially laminating a charge transport layer containing a chargetransport material and a charge generating layer containing a chargegenerating material or laminating these layers vice-versa.Alternatively, a single-layer photosensitive layer containing both acharge transport material and a charge generating material may beformed.

[0047] The charge transport layer is formed by coating a compositioncomprising a charge transport material, a binder and an organic solventand thereafter drying the layer. The charge generating layer is formedby coating a composition comprising a charge generating material, abinder and an organic solvent and thereafter drying the layer.

[0048] Examples of the charge transport material include, but are notlimited to, pyrazoline derivatives, fluorene derivatives, oxadiazolederivatives, stilbene derivatives, hydrazone derivatives, carbazolehydrazone derivatives, triaryl amines, polyvinyl carbazole, polyvinylpyrene, and polyacenaphthylene.

[0049] Examples of the charge generating material include, but are notlimited to, metal-free phthalocyanine (e.g., Progen 1x-form metal-freephthalocyanine, ZENECA INC.), and metal phthalocyanine such as titaniumphthalocyanine, copper phthalocyanine, titanyloxy phthalocyanine, orhydroxygallium phthalocyanine.

[0050] The charge transport material may be used in a generally acceptedamount, that is, in an amount of 35 to 65 parts by weight based on 100parts by weight of the composition for forming the charge transportlayer. The charge generating material may be used in an amount of 55 to85 parts by weight based on 100 parts by weight of the composition forforming the charge generating layer.

[0051] The binder may dissolve or disperse the charge transport materialor charge generating material, and examples thereof include, but are notlimited to, polyvinyl butyral, polycarbonate, poly(styrene-co-butadiene), modified acryl polymer, polyvinyl acetate,styrene-alkyd resin, soya-alkyl resin, polyvinyl chloride,polyvinylidene chloride, polyacrylonitrile, polyacrylic acid,polyacrylates, polymethacrylates, styrene-based polymers, alkyd resin,polyamides, polyurethanes, polyesters, polysulfones, polyethers andmixtures thereof. In the present invention, polycarbonate or polyvinylbutyral is preferably used. The binder is used in an amount of 15 to 65parts by weight, based on 100 parts by weight of the composition forforming the charge generating layer or the charge transport layer.

[0052] Examples of the organic solvent used for the charge transportlayer forming composition or charge generating layer forming compositioninclude, but are not limited to, tetrahydrofuran, methylene chloride,chloroform, dichloroethane, trichloroethane, chlorobenzene, andacetatebased solvent. The amount of the organic solvent may be in arange of 70 to 99 parts by weight based on 100 parts by weight of thecomposition for forming the charge generating layer or the chargetransport layer.

[0053] The charge transport layer forming composition or the chargegenerating layer forming composition may be coated in accordance withany appropriate technique known in the art without limitation. In thecase where the electrically conductive substrate is a drum-likesubstrate, ring coating or dip coating is preferably used.

[0054] As described above, after the photosensitive layer is formed onthe electrically conductive substrate, the composition for an overcoatlayer according to the present invention is coated on the photosensitivelayer and dried, thereby completing the organophotoreceptor according tothe present invention. The drying is performed at 80 to 140° C.,preferably at 100 to 130° C.

[0055] The composition for an overcoat layer may be coated by spincoating, dip coating or ring coating. In the case where the electricallyconductive substrate is a drum-like substrate, ring coating or dipcoating is preferably used.

[0056] In the organophotoreceptor according to the present invention,the overall thickness of the photosensitive layer may be between 5.1 to26 μm. The thickness of the charge generating layer is in the range of0.1 to 1.0 μm, the thickness of the charge transport layer is in therange of 5 to 25 μm, and the thickness of the electrically conductivesubstrate, in particular, the drum-like substrate, is generally in therange of 0.5 to 2 mm. The overcoat layer has a thickness of 0.01 to 5μm, as described above.

[0057] The organophotoreceptor according to the present invention mayfurther include additional layers. These additional layers are widelyknown layers, for example, a charge blocking layer. The charge blockinglayer may inhibit charge infusion from the electrically conductivesubstrate to the photosensitive layer or may enhance adhesion betweenthe electrically conductive substrate and the photosensitive layer.

[0058] In the electrophotographic imaging process using theorganophotoreceptor, the toner can be either a dry toner or a liquidtoner.

[0059] If the conventional organophotoreceptor for dry toner is employedin electrophotography using liquid toner, the organophotoreceptorcontacts a paraffinic solvent, a component of liquid toner, resulting incracking or crazing or partial elution of components of theorganophotoreceptor.

[0060] On the other hand, since the organophotoreceptor according to thepresent invention is highly resistant to a paraffinic solvent, it can beused for an electrophotographic imaging process using liquid toner andthe various problems associated with the prior art can be avoided. Also,the organophotoreceptor according to the present invention exhibits goodabrasion resistance in the presence of liquid toner.

[0061]FIG. 2 is a schematic representation of an electrophotographicimaging apparatus 30. The electrophotographic imaging apparatus 30includes an organophotoreceptor unit. The organophotoreceptor unitgenerally includes a drum 28 that is attachable to and detachable fromthe electrophotographic apparatus 30, and an organophotoreceptor 29disposed on the drum 28. The imaging apparatus further includes acharging device 25 which charges the organophotoreceptor unit, animagewise light irradiating device 22 which irradiates the chargedorganophotoreceptor unit with imagewise light to form an electrostaticlatent image with a toner to form a toner image on theorganophotoreceptor unit, and a transfer device 27, which transfers thetoner image onto a receiving material, such as paper P. The chargingdevice 25 may be supplied with a voltage as a charging unit and maycontact and charge the organophotoreceptor 29. Where desired, theapparatus may also include a pre-exposure unit 23 to erase residualcharge on the surface of the organophotoreceptor 29 to prepare for anext cycle. The imaging apparatus further includes anelectrophotographic cartridge 21, a developing device 24 which developsan electrostatic latent image formed on the organophotoreceptor 29, anda cleaning device 26 which cleans a surface of the organophotoreceptor29.

[0062] The electrophotographic imaging apparatus according to thepresent invention also comprises a plurality of support rollers (notshown), and an organophotoreceptor operably coupled to the supportrollers where motion of the support rollers results in motion of theorganophotoreceptor. The organophotoreceptor comprises an electricallyconductive substrate, a photosensitive layer formed on the electricallyconductive substrate, and an overcoat layer formed by coating thecomposition for an overcoat layer on the photosensitive layer and dryingthe layer.

[0063] An electrophotographic imaging process using theorganophotoreceptor according to the present invention will now bedescribed.

[0064] First, the surface of an organophotoreceptor having anelectrically conductive substrate, where a charge transport material anda charge generating material are provided, is uniformlyelectrostatically charged, and thereafter the charged surface isimagewise exposed to light. The light exposure selectively dissipatesthe charge in illuminated areas, thereby forming a pattern of chargedand uncharged areas. Finally, a liquid or dry toner is deposited on thesurface to create a toner image on the surface of the substrate. Theresulting toner image can be transferred to a suitable receiving surfacesuch as paper. The imaging process may be repeated many times.

[0065] The liquid toner is prepared by dispersing a colorant, a binderresin, a charge control agent and the like in a liquid carrier.

[0066] Examples of the liquid carrier include aliphatic hydrocarbonssuch as n-pentane, hexane or heptane, alicyclic hydrocarbons such ascyclopentane or cyclohexane, aromatic hydrocarbons such as benzene,toluene or xylene, halogenated aliphatic hydrocarbons such aschlorinated alkane, fluorinated alkane or chlorofluorocarbon, siliconoils or mixtures thereof. Specifically, aliphatic hydrocarbon solvents,in particular, paraffin solvent mixtures such as ISOPAR G, H, L, K, V orM, or NORPAR 12, 13, or 15 (Trade name) available from EXXON, arepreferably used. The amount of the solvent is 5 to 100 parts by weightbased on 1 part by weight of the colorant.

[0067] Useful colorants are well known in the art, and include materialssuch as dyes, stains, and pigments. Examples of suitable colorantsinclude, but are not limited to, phthalocyanine blue (C.I. PIGMENTBLUE), monoarylide yellow, diarylide yellow, arylamide yellow, azo red,quinacridones, magenta and black pigments, such as finely dividedcarbon, and the like.

[0068] Hereinafter, the present invention will be described in greaterdetail with reference to the following examples. The following examplesare for illustrative purposes and are not intended to limit the scope ofthe invention.

EXAMPLE 1

[0069] A charge transport layer was formed as follows: 2 g of ahydrazone-based charge transport material (of the following formulasynthesized from U.S. Pat. No. 6,066,426), and 2 g of polycarbonate(PCZ200, Mitsubishi Chemical, Japan) were dissolved in 16 g oftetrahydrofuran (THF), the solution was then filtered using a syringefilter having a pore size of 1 μm, and coated on an aluminum drum at aspeed of 300 mm/min using a ring coater, giving a charge transport layerhaving a thickness of approximately 8 μm.

[0070] Next, a charge-generating layer is formed as follows. 0.84 g ofpolyvinylbutyral (BX-1, available from SEKISUI CO., Japan) was dissolvedin 17.2 g of ethanol, and then 1.96 g of titanyloxy phthalocyanine(TiOPc, available from H. W. SANDS), as a charge generating material,was mixed to the solution. This mixture was milled in an attritionmiller for 1 hour. 4.29 g of the resulting milled dispersion was dilutedwith 10.1 g of butylacetate and 0.63 g of ethanol and filtered through asyringe filter having an average pore size of 5 μm to provide a chargegenerating layer coating composition. The coating composition was coatedon the charge transport layer at a speed of 250 mm/mm using a ringcoater, thereby forming a charge generating layer having a thickness ofapproximately 0.3 μm.

[0071] Then, an overcoat layer is formed as follows. 0.3 g ofpolyaminoether (Blox 205, Dow Chemical), 0.06 g ofbutyl-9-dicyanomethylenefluorene-4-carboxylate of the following formula,9.7 g of 1-methoxy-2-propanol (Dowanol-PM) were completely dissolved,giving a coating solution. The coating solution was coated using a ringcoater at a speed of 200 mm/min and dried at 120° C. for 20 minutes,thereby obtaining an overcoat layer having a thickness of approximately1 μm.

COMPARATIVE EXAMPLE

[0072] An organophotoreceptor was manufactured in the same manner as inExample 1 except that 0.3 g of polyaminoether (Blox 205, Dow Chemical)and 9.7 g of 1-methoxy-2-propanol, (Dowanol-PM) were used in preparingthe overcoat layer.

[0073] The charge potential and the exposure potential of the organicphotoreceptors prepared in Example and Comparative Example were measuredwhile repeating 100 charge-exposure-erase cycles, using a drumphotoreceptor evaluation apparatus (PDT2000, available from QEA). Acorona voltage +8.0 kV was applied to the photoreceptors charged with arelative speed of a charger and the photoreceptor being 100 mm/sec,immediately followed by irradiating monochrome light having a wavelengthof 780 nm at a constant exposure energy of 1 mJ/m². TABLE 1 Theevaluation result is shown in Table 1. Evaluation item ExampleComparative Example Charge potential (V) 552 → 550 537 → 545 Exposurepotential (V) 103 → 107 112 → 119 E_(1/2) (mJ/m²) 0.327 0.367 E₂₀₀(mJ/m²) 0.482 0.541

[0074] Referring to Table 1, the overcoat layer prepared in Example 1,containing butyl-9-dicyanomethylenefluorene-4-carboxylate, showed aninitial exposure lower than that of the overcoat layer usingpolyaminoether without butyl-9-dicyanomethylenefluorene-4-carboxylate ofthe Comparative Example. Also, in the overcoat layer of the presentinvention, an increase in exposure potential was not so great incharge-exposure-erase cycling. Further, photosensitivity of the overcoatlayer of the present invention, as expressed by a reciprocal number of E_(1/2) or E ₂₀₀, was greatly increased.

[0075] In an electrophotographic imaging process, since theorganophotoreceptor comprising an overcoat layer formed using theovercoat layer forming composition can maintain high charge potentialand low residual or discharge potential, the lifetime of theorganophotoreceptor can be extended. Also, since the organophotoreceptoraccording to the present invention has good solvent resistance andabrasion resistance, it can be advantageously used for liquid toner.

[0076] Although a few embodiments of the present invention have beenshown and described, it would be appreciated by those skilled in the artthat changes may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A composition for forming an overcoat layer foran organophotoreceptor comprising: polyaminoether; an electron transportmaterial; and an alcoholic solvent.
 2. The composition of claim 1,wherein the polyaminoether is hydroxylated polyaminoether.
 3. Thecomposition of claim 1, wherein the polyaminoether is represented by thefollowing formula, and is contained in an amount of 70 to 99 parts byweight based on 100 parts by weight of the solid content of an overcoatlayer:

wherein n is an integer from 10 to
 400. 4. The composition of claim 1,wherein the electron transport material contains an electron transportmaterial represented by the following formula:

wherein A and B are independently one selected from the group consistingof a hydrogen atom, a halogen atom, a C2˜C30 substituted orunsubstituted alkoxycarbonyl group or a C2˜C30 substituted orunsubstituted alkylaminocarbonyl group, and the hydrogen atoms in thebenzene ring is substitutable by a halogen atom.
 5. The composition ofclaim 1, wherein the amount of the electron transport material is in therange of 1 to 30 parts by weight based on 100 parts by weight of thesolid content of an overcoat layer.
 6. The composition of claim 1,wherein the alcoholic solvent is at least one selected from the groupconsisting of 1-methoxy-2-propanol, methanol, ethanol, propanol, butanoland isopropanol, and is contained in an amount of 70 to 99 parts byweight based on 100 parts by weight of the composition for an overcoatlayer.
 7. An organophotoreceptor comprising: an electrically conductivesubstrate; a photosensitive layer formed on the electrically conductivesubstrate; and an overcoat layer formed by coating the composition ofany one of claims 1, 2, 3, 4, 5 and 6 on the photosensitive layer anddrying.
 8. The organophotoreceptor of claim 7, wherein the overcoatlayer has a thickness of 0.01 to 5 μm.
 9. The organophotoreceptor ofclaim 7, wherein the photosensitive layer is a single layer having botha charge generating material and a charge transport material.
 10. Theorganophotoreceptor of claim 7, wherein the photosensitive layer is adouble layer in which a charge generating layer containing a chargegenerating material and a charge transport layer containing a chargetransport material are laminated.
 11. An electrophotographic imagingapparatus comprising: a plurality of support rollers; and anorganophotoreceptor operably coupled to the support rollers where motionof the support rollers results in motion of the organophotoreceptor,wherein the organophotoreceptor comprises an electrically conductivesubstrate, a photosensitive layer formed on the electrically conductivesubstrate, and an overcoat layer formed by coating the composition ofany one of claims 1, 2, 3, 4, 5 and 6 on the photosensitive layer anddrying.
 12. The electrophotographic imaging apparatus of claim 11,wherein the overcoat layer has a thickness of 0.01 to 5 μm.
 13. Theelectrophotographic imaging apparatus of claim 11, wherein thephotosensitive layer is a single layer having both a charge generatingmaterial and a charge transport material.
 14. The electrophotographicimaging apparatus of claim 11, wherein the photosensitive layer is adouble layer in which a charge generating layer containing a chargegenerating material and a charge transport layer containing a chargetransport material are laminated.
 15. An electrophotographic cartridge,comprising: an organophotoreceptor comprising an electrically conductivesubstrate, a photosensitive layer formed on the electrically conductivesubstrate, and an overcoat layer formed by coating a composition on thephotosensitive layer and drying the overcoat layer; a charging devicethat charges the organophotoreceptor; a developing device which developsan electrostatic latent image formed on the organophotoreceptor; and acleaning device which cleans a surface of the organophotoreceptor,wherein the electrophotographic cartridge is attachable to anddetachable from an image forming apparatus.
 16. The electrophotographiccartridge of claim 15, wherein the composition to be coated on thephotosensitive layer comprises: a polyaminoether; an electron transportmaterial; and an alcoholic solvent.
 17. The electrophotographiccartridge of claim 16, wherein the polyaminoether is hydroxylatedpolyaminoether.
 18. The electrophotographic cartridge of claim 16,wherein the polyaminoether is represented by the following formula, andis contained in an amount of 70 to 99 parts by weight based on 100 partsby weight of the solid content of an overcoat layer:

wherein n is an integer from 10 to
 400. 19. The electrophotographiccartridge of claim 16, wherein the electron transport material containsan electron transport material represented by the following formula:

wherein A and B are independently one selected from the group consistingof a hydrogen atom, a halogen atom, a C2˜C30 substituted orunsubstituted alkoxycarbonyl group or a C2˜C30 substituted orunsubstituted alkylaminocarbonyl group, and the hydrogen atoms in thebenzene ring can be substituted substitutable by a halogen atom.
 20. Theelectrophotographic cartridge of claim 16, wherein the amount of theelectron transport material may be is in the range of 1 to 30 parts byweight based on 100 parts by weight of the solid content of an overcoatlayer.
 21. The electrophotographic cartridge of claim 16, wherein thealcoholic solvent is at least one selected from the group consisting of1-methoxy-2-propanol, methanol, ethanol, propanol, butanol andisopropanol, and is contained in an amount of 70 to 99 parts by weightbased on 100 parts by weight of the composition for an overcoat layer.22. An electrophotographic drum, comprising: a drum that is attachableto and detachable from an electrophotographic apparatus; and anorganophotoreceptor comprising an electrically conductive substrate, aphotosensitive layer formed on the electrically conductive substrate,and an overcoat layer formed by coating a composition on thephotosensitive layer and drying the overcoat layer.
 23. Theelectrophotographic drum of claim 22, wherein the composition to becoated on the photosensitive layer comprises: a polyaminoether; anelectron transport material; and an alcoholic solvent.
 24. Theelectrophotographic drum of claim 23, wherein the polyaminoether ishydroxylated polyaminoether.
 25. The electrophotographic drum of claim23, wherein the polyaminoether is represented by the following formula,and is contained in an amount of 70 to 99 parts by weight based on 100parts by weight of the solid content of an overcoat layer:

wherein n is an integer from 10 to
 400. 26. The electrophotographic drumof claim 23, wherein the electron transport material contains anelectron transport material represented by the following formula:

wherein A and B are independently one selected from the group consistingof a hydrogen atom, a halogen atom, a C2˜C30 substituted orunsubstituted alkoxycarbonyl group or a C2˜C30 substituted orunsubstituted alkylaminocarbonyl group, and the hydrogen atoms in thebenzene ring can be substituted substitutable by a halogen atom.
 27. Theelectrophotographic drum of claim 23, wherein the amount of the electrontransport material may be is in the range of 1 to 30 parts by weightbased on 100 parts by weight of the solid content of an overcoat layer.28. The electrophotographic drum of claim 23, wherein the alcoholicsolvent is at least one selected from the group consisting of1-methoxy-2-propanol, methanol, ethanol, propanol, butanol andisopropanol, and is contained in an amount of 70 to 99 parts by weightbased on 100 parts by weight of the composition for an overcoat layer.